Help! Need help with windshield wiper malfunction!

Hey all, DIY guy here. I'm stuck in finding a solution for this annoying problem I have with my wipers.

When it rains, my 2010 Prius base's front windshield wipers stall intermittently in the low (variable frequency) and medium speed settings. The wipers may work for a short period of time and will stall in either the horizontal or vertical position. This started right after I removed and reinstalled the wiper motor assembly to do a spark plug replacement. The only speed that works consistently is the fastest speed setting (level 3). In the event of a stall, I can get the wipers unstuck by turning the speed to the fastest setting. But if I reduce the speed to the earlier malfunctioning speeds and it is still raining, the wipers may or may not work. If it works, it does so shakily like it lost some power and will eventually stall again. The length of time it takes to stall again at this point varies from a couple of seconds to a few minutes. I have tried disconnecting and tightening the electrical spring connections in the wiper motor’s electrical connectors to see if a tighter fit will fix the problem. This seems to have worked for a few rainy days and the problem reappeared.

It's the weirdest thing - the wipers only stall when there's a lot of rain. If there's only slight rain, it may work normally or with a jerky reduced power motion. It always works perfectly when dry (once I've got them unstuck). I don't think the wiper motor is bad because it works well when it's not pouring. I'm thinking of using electrical contact cleaner and dielectric grease next. Any ideas?

 

Thumbs up for your input. I'm gonna try insulating the connector from the rain with some saran wrap and duct tape and see if that works. I want to test and report the results of this solution but I gotta wait till I get my car back from the body shop

 

Great idea. I thought it was a sealed unit but now I'm gonna have to get in there to see what's up.

 

Update: so I opened up the wiper motor gearbox and found that 2 of the 3 carbon brushes were really worn down. I guess those are used for speeds 1 and 2 which are used more often, and when energized, they probably wear faster if I'm not mistaken. There's still some life left on the brushes so hopefully a cleaning will fix the problem. There's a whole bunch of carbon crud buildup inside the casing from all the carbon brush grinding on the commutator. As you can see I took a pic of the brush assembly on mine, but I also inserted some general brushed motor pics for anyone having the same issues to understand how this all works because I was too lazy to take pics of those parts from my own motor.





So I just cleaned up all the carbon crud and reinstalled everything and it seems to work fine again, but it hasn't been rain and snow tested yet. The problem seems to occur more frequently in cold, wet and snowy conditions so I'll try to post another update on that if I can. I'll get a new motor but for now I'll just keep using this one while waiting for a new motor to ship.

I sucks that Toyota doesn't make a replacement brush assembly though, as the motor will continue to last forever like most Toyota if they did. Getting a new motor seems like such a waste of a strong rotor coil pack that works. I say this because the brush assembly was easily removable after releasing 2 Phillips screws in the pic smh

 

Thanks for the ideas! I thought about replacing the brushes individually but it seems that the wires and soldering points are too small for my skill level. Maybe some shops may sell the brush assemblies.

 

Update: Snow, rain, and cold tested. Just a simple cleaning solved the problem. Should last at least another couple of years

 

I'm revisiting this thread I started long ago.

I need a new wiper motor for my gen 3 and I want to get one from a wreck.

The gen 3 wiper motor numbers start with 85110 but have different ending numbers. This parts catalog shows gen 3 wiper motors with different ending numbers for different years:
85110-57100
85110-57110
85110-57190
85110-57200

The following is what is advertised as a gen 3 wiper motor on Ebay. Its part number is shown as 85110-47240.


The following is what is advertised as a 2016-17 Prius Prime wiper motor on Ebay. Its part number is shown as 85110-47290 and looks identical in shape to the previous part.


The first pic also says "12V 5Q" and the second says "12V 2T". What do these numbers 5Q and 2T mean? Does anyone know what other Toyota/Lexus cars that have wiper motors that will fit on a gen 3?